#include <stdio.h>

int main()
{
	int g = 0;
	int ret = 0;
	printf("请输入成绩>");
	scanf("%d", &g);
	ret = g / 10;
	switch(ret)
	{
	case 10:
	case 9:
		printf("A\n");
		break;
	case 8:
		printf("B\n");
		break;
	case 7:
		printf("C\n");
		break;
	case 6:
		printf("D\n");
		break;
	default:
		printf("不及格！\n");
	}

	return 0;
}
